1. Field of the Invention
The present invention is related generally to implantable medical electrical leads. More specifically, the present invention is related to implantable neurological leads.
2. Prior Art
Spinal cord and other neurological stimulations by electrical leads are used for many purposes, including pain masking. One lead design that has been particularly useful is the so called “transverse tripole” electrode arrangement. This contact arrangement includes a set of three electrodes positioned transversely to the axis of the spinal cord. The center electrode is generally the cathode, with either or both of the lateral electrodes acting as return anodes. It is desirable to have multiple sets of contacts to allow for reprogramming of the system to accommodate patient movement, change in disease state, and the like. The multiple sets of contacts may also be used to “steer” electrical stimulation into a desirable pattern.
For a transverse tripole contact arrangement, the current state of the art requires the percutaneous implantation of three separate electrode carrying leads. Each lead must be individually moved through an appropriately sized needle and properly positioned. Since positioning three leads requires multiple punctures with a needle, the procedure is understandably both challenging and time consuming. Alternatively, a surgical paddle type lead can be used. This requires an open surgical technique such as a laminotomy or laminectomy to place the paddle along the spinal cord. Needless to say, such invasive procedures are not desirable.
In that respect, a lead is needed that provides for percutaneous implantation of a multiple transverse tripole electrode array via a single standard needle stick. The presently described invention provides a lead with just such an electrode array.